Personally I'd take still take the Managers exam as you have it booked. The core principles of Service Delivery & Service Support won't change. I faced a simlar dilema when V1 went to V2 and continued to take the V1 Managers exam. My rational was it's like Microsoft uprages.. go with what's established as the fundamentals won't change!.

The books are due out 30th May, I doubt the training providers will get much pre-visibility to adapt their courseware. My take on 'stable' V3 exams will be back end of this year.

No problem. My understanding is that currently there will be no upgrade exam as such just an overview outlining the differences between V2 & V3. I'm presuming this will be an offering by the Training Companies but i'm not sure of their cost models.

I don't believe there was an upgrade exam from V1 to V2 either( I certainly never took one), just awareness sessions run by the Training Companies.